Due to an increasing number of wireless devices and a growing demand for wireless services, wireless communication systems continue to expand. To meet the growing demand, wireless providers have deployed a greater number of wireless transmitters. As an alternative, however, wireless providers have also utilized relay-based systems.
In a relay-based system, one node of a wireless system may communicate with another node in the wireless system using one or more intermediary nodes, called relay nodes. In some systems, the relay node may be referred to as a relay station, and the combination of nodes and connections between an originating node and a destination node may be referred to as a transmission path. Relay-based systems may be found in any type of wireless network.
An example of a relay-based system is a multi-hop relay (MR) network. FIG. 1 is a diagram of a conventional MR network 100 based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16 family of standards. As shown in FIG. 1, MR network 100 may include one or more transmitters, e.g., base station (BS) 110, one or more relay stations (RS) 120, including RSs 120a, 120b, and 120c, one or more subscriber stations (SS) 130, including SSs 130x, 130y, and 130z, and one or more transmission paths (TP) 140, including TP 140a and TP 140b. 
In MR network 100, communication between a transmitter station (e.g., BS 110) and subscriber stations (e.g., SS 130x, SS 130y, SS 130z, etc.) may be achieved using one or more relay stations (e.g., RS 120a, RS 120b, RS 120c, etc.). For example, in MR network 100, RS 120a may receive data from BS 110 and send the data to another relay station (e.g., RS 120b). Alternatively, RS 120a may receive data from a downstream relay station (e.g., RS 120b), and send it to BS 110. As another example, RS 120b may receive data from RS 120a and send the data to a supported subscriber station (e.g., SS 130y). Alternatively, RS 120b may receive data from a subscriber station (e.g., SS 130y), and send it to an upstream relay station (e.g., RS 120a).
As shown in FIG. 1, transmission path (TP) 140 may be the transmission route from BS 110 through the one or more RSs 120. For example, the transmission route from BS 110 to RS 120b (i.e., TP 140a) may include BS 110, RS 120a, and RS 120b. The transmission route from BS 110 to RS 120c (i.e., TP 140b) may include BS 110 and RS 120c. 
Because transmission paths may vary in their lengths, the length of time for a broadcast transmission packet to move along different transmission paths may also vary. Thus, when BS 110 transmits data along multiple transmission paths, the final relay stations in each of the various transmission paths may receive their data at different times. The final relay stations may, in turn, transmit the data to their subscriber stations at different times, thereby causing the subscriber stations to receive the data at different times.
Thus, there is a need for systems and methods that ensure the synchronous transmission of broadcast data packets from relay stations, varying in their transmission latency, along transmission paths of varying lengths. Additionally, there is a need for systems and methods to ensure synchronous transmission of broadcast and multicast data in multi-hop transmission systems.
The disclosed embodiments are directed to overcoming one or more of the problems set forth above.